3.

(a) Photos of virgin hair (left), H2O2-permed hair (middle) and SHB-permed hair (right) after repeated perming; (b) perming efficiency of three hair samples (t-test, *means 0.01 < p < 0.05, **means 0.001 < p < 0.01).

(a) Photos of virgin hair (left), H2O2-permed hair (middle) and SHB-permed hair (right) after repeated perming; (b) perming efficiency of three hair samples (t-test, *means 0.01 < p < 0.05, **means 0.001 < p < 0.01).